Seals for rotary and axially movable shafts

ABSTRACT

A seal for a rotary and axially movable shaft comprises a stationary outer element and an inner element axially guided in said outer element but freely rotatable therein, said inner element consisting of a sealing lip which is in elastic engagement with the shaft, a main portion in sealing elastic engagement with the outer element, and a collar interconnecting said two details, the engagement of the sealing lip with the shaft being stronger than that of the main portion with the outer element.

United States Patent [1 1 Hansson Sept. 25, 1973 1 1 SEALS FOR ROTARYAND AXIALLY MOVABLE SHAFTS [75] Inventor: Hans John Olof Hansson,Halmstad,

Sweden [73] Assignees: Lars Jan Herman Hanson; Anders Walter Andersson,Halmstead, Sweden [22] Filed: Dec. 10, 1970 [21] Appl. No.: 96,958

[52] US. Cl 277/37, 277/65, 277/206 R [51] Int. Cl Fl6j 15/32 [58] Fieldof Search 277/35, 25, 37, 38,

[56] I References Cited UNITED STATES PATENTS 2,888,281 5/1959 Ratti277/25 3,442,516 5/1969 Voitik 277/3) 3,179,424 4/1965 Carson et a1.277/39 X 3,545,774 12/1970 Rickley 277/235 Primary ExaminerGeorge E.Lowrance Assistant Examiner-Robert I. Smith Att0rneyJohn Lezdey 5 7]ABSTRACT A sea] for a rotary and axially movable shaft comprises astationary outer element and an inner e1ement axially guided in saidouter element but freely rotatable therein, said inner elementconsisting of a sealing lip which is in elastic engagement with theshaft, a main. portion in sealing elastic engagement with the outer e14ement, and a collar interconnecting said two details, the engagement ofthe sealing lip with the shaft being stronger than that of the mainportion with the outer element.

1 Claim, 15 Drawing Figures PATENTEDSEF25 I975 SHEET U BF 4 SEALS FORROTARY AND AXIALLY MOVABLE SHAFTS This invention relates to a seal for arotary and axially movable shaft ofsubstantially circular cross sectionin a substantially circular duct between two spaces to be sealed fromone-another, said seal comprising an outer element of the same shape asthe duct and retained therein, and an inner element which is preventedfrom moving axially in said outer element by axial guide means but isfreely rotatable therein.

Experiences earlier made in machine constructions have shown that apartfrom a satisfactory sealing capacity for the purpose concerned a sealshould have the following two essential properties:

l. The seal must not cause damage to machine parts, preferably the shaftto be sealed, by scoring it. Such an undesirable wear is disadvantageousin several respects; first of all the wear may result in leakage, but inthe long run scoring of the shaft may become so pronounced that norenewed sealing can be obtained although a new seal is mounted.Besides,scoring of a shaft may lead to rupture, and as a secondaryeffect the leakage may damage other machine elements.

2. In many casesthe seal should be readily axially movable, for instanceon a shaft, with retained sealing ability. With axially movable seals,mountingand dismounting operations will be simplified.

Various constructions are previously known for overcoming thedisadvantage mentioned in item 1. Generally, these constructions operatewith a seal that is stationary with respect to the shaft, the relativemovement occurring in the seal itself. Examples of such constructionsare given in Swedish Pat. Nos. 204,587, 222,61 1, 302,550, German Pat.Nos. 717,627, 972,476, 1,027,944, French Pat. Nos. 936,483, 1,145,882,1,267,966, 1,446,753 and U.S. Pat. Nos. 2,240,252, 2,478,140, 2,784,017.However, none of these constructions allow the axial movabilitymentioned in item 2, which mostly is not only essential but evennecessary.

The present invention thus relates to a seal of the type outlined in theforegoing. Characteristic of this seal is that the inner elementconsists of a sealing lip which is in sealing elastic engagement withthe shaft by the action of a biasing spring, a main portion in sealingelastic engagement with the outer element, and a collar which allowsradial shaft movements, wholly interconnects the sealing lip and themain portion and extends mainly axially, and upon rotary shaft movementonly the engagement of the sealing lip with the shaft is strong enoughby reason of the dimensions of the biasing spring and the sealing lip toovercome the total frictional resistance arising from the axial guidemeans and the engagement of the main portion with the outer element sothat all relative sliding movement in this case takes place between themain portion and the outer element, but upon axial and combined axialand rotary shaft movements is loose enough to allow axial movements withretained sealing capacity.

The invention will now be described in more detail hereinbelow withreference to the accompanying drawings in which:

FIG. 1 shows a side view, partly in section, of a shaft sealed in ashaft duct by means of a seal according to the invention;

FIGS. 2-8 show sections of various structural embodiments of the seal,FIGS. 5a, 7a, b, c and 8a illustrating details of FIGS. 5, 7 and 8,respectively;

FIG. 9 shows a perspective view, with certain parts broken away, of astructurally suitable embodimentof the seal according to the invention;

FIG. 9a shows a section of the seal in FIG. 9.

The same details have been given the same reference numerals in thevarious embodiments.

FIG. 1 shows a seal according to the invention in gripping engagementwith a shaft 1 which can effect a rotary and also axial movement, as isindicated by the arrows. The seal arranged in the shaft duct comprisestwo main elements, namely an outer element 2 of metal or other suitablestructural material which is fixedly arranged in the shaft duct, and aninner element 3 which predominantly consists of rubber and like materialhaving elastic properties. v

Provided between the outer and inner elements is positive axial guidemeans which in the case illustrated in FIG. 1 is realized in that theouter element has an inwardly extending flange 2' and the inner elementhas a guide channel 3' in the form of a groove which is fixedlyvulcanized to the rubber detail. The dimensions of the flange 2' and thechannel 3 are such that the channel can substantially freely rotate inrelation to the v flange.

The inner element 3 elastically engages the shaft 1 on .the one hand andthe outer element 2 on the other hand, the shaft engagement beingensured by a biasing spring 4 in a conventional manner. By reason ofsuitable dimensions the engagement conditions of the inner element withthe shaft and the outer element are such that the relative movement andthus the wearing sliding movement upon rotation of the shaft occursbetween the inner and the outer element at 5, whereas the inner elementrotates withoutany sliding movement together with the shaft. Upon axialmovement, however, the inner element of the seal thanks to the axialguide means must slide with respect to the shaft without,

7 however, causing any direct wear of the shaft.

By this fundamentally new construction it is realized on one hand thatno wear is exerted on the shaft which can therefore be manufacturedwithout placing the usual high requirements on material and surfacefinish, and on the other hand that the elements of the seal which aregradually worn out can easily be exchanged, so that fullsealing capacityis again established.

The embodiment illustrated in FIG. 1 has for its purpose to provide sealagainst pressure from one side,

whereas the embodiment illustrated in FIG. 2 is intended to provide sealagainst pressure from two sides.

The fundamental construction otherwise is the same,

and it is thus possible to discern the outer element 2, the innerelement 3, the biasing ring or spring 4, and the axial guide means whichin the present instance is built up of parts separate from the outerelement to permit a more free choice of materials.

The embodiment illustrated in FIG. 3 corresponds both to thatillustrated in FIG. 1 and to that illustrated in FIG. 2 and is intendedto .providea seal against pressure from one side. However, the innerelementis provided with a lip 6 sealing against dust or insignificantpressure from the other side.

In the embodiments hitherto described the inner element was in the formof an elastic detail fixedly vulcanized to a separate guide member, butit is also conceivable to make the inner element entirely of rubber orlike material. An example of such a design is shown in FIG. 4. Here, theouter element 2 is made of bent sheet metal, nylon or the like and isprovided with a guide flange 2. The inner element 3 has been providedwith reinforcing steel disks 7 which are placed in suitable slits andprevent the inner element from being forced out of the outer elementwhen the seal is in operation. To reduce friction at the axial guidemeans a disk 8 of Teflon or like material is placed on either side ofthe flange 2'.

In FIG. the same outer element is provided as in FIG. 4 and also thefriction reducing rings 8, whereas the elastic portion of the innerelement is fixedly vulcanized to a sheet metal sleeve 9 having a groovefor a spring washer 10, FIG. 5a, which retains the axial guide means inposition.

The axial guide means can be designed in several different ways, specialembodiments being exemplified in FIGS. 6 and 7. In FIG. 6 the axialguide means is in the form of a ball bearing 11 which is kept clamped inposition with the aid of spring washers 12. The seal is here shown indouble-sided configuration. In the embodiment shown in FIG. 7 the outerand inner element, respectively, has a V-shaped groove in which runballs 13 (FIG. 7a), rollers 14 (FIG. 7b) or a suitably profiled strip 15(FIG. 7c) of friction reducing material. This seal also is ofdouble-sided configuration but it should be observed that this seal likethe other seals illustrated can be given a singleor double-sidedconfiguration, as desired.

The embodimeht illustrated in FIG. 8 mostly resembles the embodimentshown in FIG. 5, but in this instance the elastic element does not sealdirectly against 4 the inner circumferential surface of the outerelement but with the aid of a graphite or bakelite ring seal 16 againstthe flange 2'. This ring 16 has a groove for a ring 17 of Teflon or likematerial for reducing wear and friction. FIG. 8a shows this embodimentof the seal bearing against the outer element more in detail. On theother side of the flange 2' there is provided, in addi tion to thefriction reducing ring 8 and the retaining spring washer 10 also anaxially biasing spring 18.

I The seal illustrated in FIGS. 9 and 9a is to be regarded as anembodiment suitable for mass production, while still retaining the samefundamental principle as in the earlier embodiments. The outer element 2is a sheet metal detail bent into the configuration shown, a ring 19being provided as a reinforcement. The inner element has a reinforcingring 20 which is totally encased in the rubber. The engagement of theinner element with the outer element in this case does not take placeeither against the inner surface of the outer circumferential portion oragainst the flange 2'. but inwardly against the outer surface of theinner portion 21 of the outer element. Axial guiding here takes place bythe action of friction reducing rings 8 at the axial flange 2' and atthe inner portion of the outer element.

In all of these embodiments of seals according to the invention theouter and inner element, respectively rotates relative to the element,when the shaft rotates (is axially stationary) and no wear occursoutside the seal. At combined axial and rotary movement the shaft slidesin the inner biased collar of the inner elemnet. When the axial movementceases the outer and inner element, respectively, of the seal resumesits described rotary movement relative to the other element withoutsliding on the shaft.

In the foregoing, reference has been made to a shaft movable in a duct,but the opposite, technically equivalent relation is also conceivable,viz. that the shaft is stationary and the duct located in a movableelement such as a hub or like part. In this case, of course, the shapeof the seal is inversed. The invention can thus be realized with thesame advantages in providing such a solution.

I claim:

1. A continuous seal between a shaft of substantially circular crosssection and a member having a substantially circular duct for the shaftformed therein, the

shaft and the member being rotatable and axially movable in relation toeach other, said seal comprising:

a rigid-outer element with an axial portion having an outer diameter thesame as the inner diameter of said duct and retained by tight fittherein, said outer element having a radial portion extending towardsaid shaft,

an elastic inner element freely rotatable in said outer element, saidinner element having an inner lip with continuous sealing elasticengagement with said shaft, and an outer lip in continuous sealingengagement with the axial portion of said outer element, means having aradially outwardly opening channel secured to said inner element andreceiving said radially extending portion of said outer element withinits open channel biasing means arranged around said inner lip forcontributing to the continuous engagement of said inner lip with saidshaft, whereby the engagement of the lip with the shaft upon rotarymovement of the shaft in relation to the member being strong enough byreason of the dimensions of the biasing means and the lip to overcomethe total frictional resistance arising from said channel and radiallyextending portion of said outer element and the engagement of the outerlip with the outer element so that all relative sliding movement in thiscase takes place between the outer lip and the outer element, but onaxial and combined axial and rotary movements of the shaft in relationto said member being loose enough to allow relative axial movementsbetween said inner lip and said shaft with retained sealing capacity.

t t t

1. A continuous seal between a shaft of substantially circular crosssection and a member having a substantially circular duct for the shaftformed therein, the shaft and the member being rotatable and axiallymovable in relation to each other, said seal comprising: a rigid outerelement with an axial portion having an outer diameter the same as theinner diameter of said duct and retained by tight fit therein, saidouter element having a radial portion extending toward said shaft, anelastic inner element freely rotatable in said outer element, said innerelement having an inner lip with continuous sealing elastic engagementwith said shaft, and an outer lip in continuous sealing engagement withthe axial portion of said outer element, means having a radiallyoutwardly opening channel secured to said inner element and receivingsaid radially extending portion of said outer element within its openchannel biasing means arranged around said inner lip for contributing tothe continuous engagement of said inner lip with said shaft, whereby theengagement of the lip with the shaft upon rotary movement of the shaftin relation to the member being strong enough by reason of thedimensions of the biasing means and the lip to overcome the totalfrictional resistance arising from said channel and radially extendingportion of said outer element and the engagement of the outer lip withthe outer element so that all relative sliding movement in this casetakes place between the outer lip and the outer element, but on axialand combined axial and rotary movements of the shaft in relation to saidmember being loose enough to allow relative axial movements between saidinner lip and said shaft with retained sealing capacity.